1. Field of the Invention
The present invention relates generally to structures and assemblies for use in connection with a patient interface device, and, in particular, to an adjustable conduit coupling assembly for providing adjustability of the position and orientation of a conduit coupling that joins a patient interface device to a patient circuit.
2. Description of the Related Art
It is well known to diagnose, treat, or monitor the condition of the patient using a patient interface device that communicates with the airway of a patient. For example, a patient may be monitored and treated for various sleep disorders, such as obstructive sleep apnea (OSA), which is characterized by a collapse of at least a portion of the upper airway during sleep, central apneas, which are characterized by the suspension of all respiratory movement, or a combination of both OSA and central apneas, referred to as mixed apnea. Monitoring and treating these disorders typically involves providing a patient interface device, such as a nasal mask, nasal/oral mask, mouth mask, full-face mask, nasal cannula, nasal prongs, nasal pillows, etc., in communication with the airway of the user, such as the user's nose, mouth, or both, and delivering a pressure support therapy to the airway of the patient.
Examples of conventional pressure support devices that deliver a pressure support therapy include a continuous positive airway pressure (CPAP) device or a device that delivers a variable airway pressure. Examples of variable pressure support devices include a bi-level pressure support, which varies the pressure delivered with the patient's respiratory cycle, or a proportional positive airway pressure (PPAP) therapy, which varies the pressure based on the monitored flow (example of this include C-Flex and Bi-Flex). It is also know to vary the pressure delivered to the patient based on a monitored condition of the patient, such as whether the patient is experiences snoring, apneas, hypopneas, flow limitations, respiratory event related arousals (RERAs), upper airway resistance, etc., which is referred to as an auto-titration pressure support system, because the system attempts to control the pressure itself so as to deliver only the pressure needed to treat the medical disorder, such as sleep apnea syndrome, in particular, OSA, congestive heart failure, stroke, Cheynes-Stokes respiration, etc.
Further, there are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively, to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheotomy tube in their trachea. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation in lieu of invasive ventilation. Non-invasive ventilation and pressure support therapies involve the placement of a mask, which is typically a nasal or nasal/oral mask, on the face of patient to interface the ventilator with the airway of the patient. For purposes of the present invention, the phrase “pressure support system”, “pressure support device,” or “positive pressure support” includes any medical device or method that delivers a flow of breathing gas to the airway of a patient including non-invasive ventilation system.
Because patient interface devices are typically worn for an extended period of time, a variety of concerns must be taken into consideration. For example, in providing CPAP or other positive pressure therapy to treat OSA, the patient normally wears the mask all night long while he or she sleeps. One concern in such a situation is that the patient interface device is as comfortable as possible, otherwise the patient may avoid wearing the device, defeating the purpose of the prescribed pressure support therapy.
A typical mask type patient interface device includes a mask shell having a cushion attached to the shell that contacts the surface of the patient. The mask shell and cushion, which are referred to as the patient interface device, are held in place by a headgear assembly that wraps around the head of the patent. The patient interface device and headgear assembly form a patient interface assembly. A typical headgear assembly has flexible, adjustable straps that extend from the patient interface device to attach the mask to the patient. Other techniques for attaching a patient interface devices use a vice-like headgear that anchors at the front and back of the patient's head to support the mask on the user. See, e.g., U.S. Pat. No. 6,516,802. While such conventional patient interface devices are generally accepted, there remains a class of patients that do not find these devices to be sufficiently comfortable, too bulky, not providing a sufficient seal, or otherwise inadequate. Thus, alternative techniques for interfacing a pressure support system to the airway of a patient are desired.
In a conventional pressure support system, a flexible conduit is coupled to an outlet port of the pressure generating system. The flexible conduit is typically referred to as a “patient circuit” or “breathing circuit” and carries the flow of breathing gas from the pressure generating system to the patient interface device. In a typically arrangement, a patient interface device, such as a mask, is provided at the end of the patient circuit. A conduit coupling connects the patient circuit with the patient interface. In some arrangements, the conduit coupling is a permanent part of the mask, and, thus, forms part of the patient interface device. In other arrangements, the conduit coupling is considered part of the patient circuit. In either arrangement, the flow of gas is coupled to the airway of the patient by the patient interface device, so that the elevated pressure gas flow is delivered to the patient's airway.
Because patient interface assemblies are typically worn for an extended period of time, another concern is that the patient interface device provide a seal against the surface of the patient the is relatively fee of leaks or minimizes leaks. That is, the headgear must maintain the mask in a tight enough seal against a patient's face to be relatively leak free and do so without discomfort. Adjustability of the mask and/or the headgear, together with increased patient comfort, is also of importance. Similarly, when using a nasal mask, the conduit coupling, which couples the patient circuit to the mask (typically an rigid elbow), should be adjustable. This allows the patient to manipulate the angle, orientation, and/or position of the conduit coupling with respect to the user's face and/or forehead. As the patient engages in different activities, changes sleep positions, and over the course of time, for the sake of convenience and comfort, the conduit coupling should allow for maximum adjustability.
Various embodiments of mask assemblies are known that allow for the variable positioning of conduit couplings, and therefore the mask, as well as the conduit through which gas flows to the mask relative to the patient. For example, U.S. Pat. No. 6,823,869 discloses a mask assembly that provides for some limited adjustment of the conduit coupling with respect to the patient's face. However, the assembly of the '869 patent, while providing some adjustability of orientation and position of the conduit coupling, provides only limited adjustment options, such that the patient is not offered a limitlessly adjustable conduit coupling. A modified headgear or headgear assembly for use in positioning the patient interface and conduit coupling with respect to the patient's face is disclosed in U.S. Pat. Nos. 6,494,207 and 6,615,834.
Another conduit coupling assembly that is adjustable is disclosed in U.S. Pat. No. 6,595,214. In the '214 patent, a forehead-plate mount 9 is arranged between stops of a mask-holding part 2 and an intermediate hose 5 on an elongate tube 3. The forehead-plate mount 9 is integrally connected to a forehead plate 10, and straps are attached to the forehead plate 10 by eyelets 11 and 12. These straps are guided over the head in order for the nasal breathing mask to be held in place. The nasal breathing mask is positioned by pulling the entire unit over the head of the patient. The optimum distance between the forehead plate 10 and a mask part 1, which is a result of the anatomy of the user, i.e. of the distance between the forehead and the nose, is set by an axial adjustment of the forehead-plate mount 9 on the elongate tube 3. This axial setting is effected by means of a clamping connection between elongate tube 3 and forehead-plate mount 9. The forehead-plate mount 9 extends is a U-shaped collar 24, which is open toward the front. The inner surface of the collar has recesses 13 extending parallel to one another in the axial direction and annularly in the circumferential direction, at regular intervals. Mating annular ribs 14 are formed on the circumferential surface of the elongate tube and can be releasably inserted into these recesses 13. Accordingly, the forehead-plate mount 9 allows for the lateral adjustment of the conduit or tube.